The developments follow nearly a year of investigations into Ellingson's death. He died at Lake of the Ozarks in May 2014 while in Missouri State Police custody.

Piercy was the trooper who arrested Ellingson on suspicion of boating while intoxicated. He admitted to using the wrong life jacket on Ellingson.

Ellingson, who was handcuffed, fell off the patrol boat and drowned.

Piercy was charged with involuntary manslaughter in the case in December. If convicted, the class C felony charge under Missouri law, carries a possible sentence of seven years in prison and a fine of $5,000.